1. Technical Field of the Invention
The invention relates to a positive resist composition the property of which changes by the reaction upon irradiation with an actinic ray or radiation. More specifically, the invention relates to a positive resist composition for use in the manufacturing processes of semiconductors, e.g., IC, circuit substrates, e.g., liquid crystals and thermal heads, and for use in other photo-fabrication processes.
2. Description of the Related Art
Chemical amplification positive resist compositions are pattern-forming materials of generating an acid at the area irradiated with radiation, e.g., far ultraviolet rays, changing the solubility of the irradiated area with the actinic radiation and that of the non-irradiated area in a developer by the reaction with the acid as a catalyst, and forming a pattern on a substrate.
When a KrF excimer laser is used as the exposure light source, since resins having poly(hydroxystyrene) as a fundamental skeleton small in absorption in the area of 248 nm are mainly used, a high sensitivity, high resolution and good pattern is formed as compared with conventionally used naphthoquinonediazide/novolak resins.
On the other hand, when a light source of shorter wavelength, e.g., an ArF excimer laser (193 nm), is used as the light source, even chemical amplification resists are not sufficient, since compounds containing an aromatic group substantially show large absorption in the region of 193 nm.
Accordingly, resists containing a resin having an alicyclic hydrocarbon structure have been developed for an ArF excimer laser. In general, in the process using these chemical amplification resists, the reaction is advanced and completed by pattern exposure and post-exposure baking (hereinafter abbreviated to “PEB”)
However, resists containing a resin having an alicyclic hydrocarbon structure for an ArF excimer laser have a problem that the rate of change of the pattern line width to the temperature at the time of PEB is large in forming minute patterns having a line width of 100 nm or less (hereinafter referred to as “PEB temperature dependency”). This problem becomes conspicuous with the fining of processing line width, thus a resist composition excellent in PEB temperature dependency and capable of forming a minute pattern is required.
In the present situation that necessitates forming a minute pattern of line width of 100 nm or less, in addition to the PEB temperature dependency, the needs of the improvements of resolution and the margin of exposure amount (the rate of change of the line width to the exposure amount) are pressing, and so the development of a resist composition satisfying resolution, the margin of exposure amount and PEB temperature dependency at the same time is demanded.
Basic compounds, specifically amine compounds, are generally used in chemical amplification resist compositions for the purpose of controlling the diffusion of acids generated upon exposure. As an example of using an amine compound having an ether bond in the molecule, JP-A-10-326015 (the term “JP-A” as used herein refers to an “unexamined published Japanese patent application”) [for the purpose of the improvements of sensitivity, resolution, and environment-protecting characteristics] and JP-A-11-84639 [for the purpose of the improvements of pattern profile and the decrease of layer thickness) are heretofore known. However, at the existing circumstances, resolution, pattern profile, the margin of exposure amount and PEB temperature dependency are not simultaneously satisfied yet even in any combination as disclosed in the above patents, accordingly it is strongly desired to satisfy these characteristics at the same time.